1. Field of the Invention
This invention relates to dispensers and more specifically to structure that converts a flexible, resilient, container into a squeeze-type dispenser in which a flexible bladder within the container receives ambient displacement fluid when contents of the container is dispensed.
2. Prior Art
This invention is an improvement over the devices disclosed and claimed in U.S. Pat. Nos. 3,319,837 issued May 16, 1967 entitled "Dispensing Device" and 3,656,660 issued Apr. 18, 1972 entitled "Closure Member and Dispensing Device." The structures disclosed in those patents utilize a bladder within a flexible, resilient, container to receive and contain displacement fluid such as air that flows into the container after contents has been dispensed by squeezing. Valves associated with the dispensing outlet and air inlet, operable in response to pressure differentials, assure that displacement fluid only enters the bladder, which then maintains the remaining contents at the dispensing outlet, in effect maintaining the container always "full" until empty. The disclosed structures have the disadvantage of requiring a separate inlet to the container to facilitate keeping the displacement fluid separate from the contents. As a result, special containers must be made or closures are required that have an extra inlet and different appearance from caps of dispensers lacking the advantageous features of the patented devices. The use of a special container is particularly disadvantageous and was avoided by the closure member disclosed in said U.S. Pat. No. 3,656,660. However, the closure member disclosed included substantial structural modifications and additional apparatus, including a housing for a collapsed bladder, a separate aperture communicating to the bladder, and flexible fingers to constrain the bladder during expansion. This structure has not proved as practical from a production and marketing standpoint as desired. In addition, the dispensing valve structure in the disclosed dispensers interfered with the flow of the dispensed contents, which did not flow in a well defined stream. While that disadvantage can be overcome by recessing the valve from the outlet opening, dispensed material may accumulate in the outlet beyond the valve and harden into a plug and/or become unsanitary, depending upon the nature of the material.